Development of Treatment Process for Radioactive Wastewater Generated from Molybdenum-99 Study - 16415

Molybdenum-99 (Mo-99) high acidic waste solution was securely stored at INER for numerous years. Until 2004, the procedures of waste solution draw-out and pressure-release were accompanied, along with construction of treatment facilities. In 2009, after simulated solution and small volume Mo-99 waste solution tests, the treatment procedure was determined. Then batch-scale treatment facilities were set up. The waste solution was preserved using the instrument, along with modification of some facilities simultaneously. Ultimately all of 12 tanks of Mo-99 inorganic waste solution stored in Building 014 were finished on July, 2012. And residential 5 tanks of those solution served in Building 015B were also completed on September, 2014. A practicable process has been developed for treating radioactive waste generated from Mo-99 study, and it can effectively remove radionuclides from a nitric acid solution. At first, after the waste was sucked from the bucket, the pH value was adjusted to about 10.0 through acid-alkali neutralization. Then, an adsorbent of natural zeolite powder was added to adsorb nuclides, and two adsorption columns filled with Cs-treat and Sr-treat adsorbents were used for removing nuclear species of Cs-137 and Sr-90. In this step, the nuclear species of Cs-137 and Sr-90 contained in the liquid waste are significantly reduced to a degree for manual operation allowable. Then, nitrate ion and mercury ion were removed through another procedure. As a result, the operations were safer and more efficient than other conventional methods. Additionally, the hazard of accidental leakage caused by corrosion of the bucket after long period of storage can be effectively prevented and potential pollution threats are also eliminated. (authors)